1. Field of the Invention
The present invention relates to a terminal for connection to an electrode of a piezoelectric element using a conductive adhesive, a flexure, and a head suspension.
2. Description of Related Art
In recent years, small-sized precision information devices have rapidly been developed, and for use with such devices, a demand for micro-actuators capable of position control for minute distances is increasing. Such micro-actuators are highly needed in the field of for example, optical systems for correcting focuses and inclination angles, ink jet printers, head actuators of magnetic disk drives, and the like.
As a technique that meets this need, a magnetic disk drive with a so-called dual actuator system is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2010-086649.
The magnetic disk drive with a dual actuator system is provided with a piezoelectric element for minute driving in addition to a voice coil motor. The voice coil motor drives a carriage to which a head suspension of the magnetic disk drive is attached. The piezoelectric element is located between a base plate and a load beam of the head suspension, to minutely drive the load beam relative to the base plate in accordance with the power supplied thereto.
Thus, the dual actuator system, in addition to turning the head suspension by the voice coil motor, minutely drives a head at a distal end of the head suspension in a sway direction through the load beam due to deformation of the piezoelectric element in accordance with the power applied thereto. This enables the head to be positioned with high accuracy.
In such a dual actuator system, a flexure is attached to the load beam as a wiring member, to supply power to the piezoelectric element through the flexure. The flexure is conductively connected to the piezoelectric element frequently by a conductive adhesive. For this, the flexure has a terminal that extends from a main body of the flexure to face the electrode of the piezoelectric element. The terminal has a distal end part that adheres to an electrode of the piezoelectric element through a conductive adhesive.
The conductive adhesive, however, may largely ooze out of and spread around the distal end part of the terminal due to its setting expansion or an excess in amounts filled.
In this case, capillary phenomenon often occurs in the oozed conductive adhesive between the terminal of the flexure and the electrode of the piezoelectric element, so that the oozed conductive adhesive flows along the terminal toward the main body of the flexure. As a result, the conductive adhesive reaches an attaching part to which the piezoelectric element is attached, the attaching part being defined by a conductive member to be located around the attached piezoelectric element between the base plate and the load beam. The conductive member functions as a ground for the piezoelectric element, and therefore, the conductive adhesive that reaches the attached part causes an electrical short circuit.
To cope with this problem, Japanese Unexamined Patent Application Publications Nos. 2010-154632 and 2010-165406 disclose that a liquid stopping ring is provided at a distal end part of a terminal and a conductive adhesive is applied inside the ring.
These related arts also disclose double liquid stopping rings that are concentrically arranged or an adhesive trap that communicates with the inside of the liquid stopping ring, capable of effectively preventing the conductive adhesive from oozing out of the distal end of the terminal.
In a case where the piezoelectric element is small-sized, however, the terminal of the flexure also becomes small-sized. The small-sized terminal may not be allowed to have the double rings, adhesive trap or the like as a structure for preventing the conductive adhesive from oozing out.